1. Field of the Invention
This invention relates to the field of stretch wrapping of panels and more particularly to methods for electrically heating panels to be stretch wrapped.
2. Prior Art
Prior art methods of stretch wrapping of panels, such as honeycomb panels, involve the welding of tabs to the panel to provide a member through which tension may be applied during the wrapping process, and also to provide an electrical contact so that heating current can be passed through the panel. The tab and panel must be long enough to allow relatively large sized electrical bus bars to be connected to the panel, since it is common to require 10,000 to 15,000 amperes of current for heating the panel to the proper forming temperature.
The electrical connections have previously been made by clamping bus bars directly to the panel to be stretch wrapped. Difficulties have been encountered with the prior art methods of making the electrical connection, which the present invention is intended to overcome. Due to the large conductors and currents involved, it is is difficult to get a sufficient clamping area to prevent localized overheating of the panel. Achieving a sufficient number of good connections between the bus bars and the panel to provide even heating of the entire panel is also a problem which has had no easy solution in the prior art.